Vermont lawmakers this week approved a bill to regulate for the first time police use of automatic license plate readers and require law enforcement to dispose of the potentially sensitive information after 18 months.

The measure, which Gov. Peter Shumlin said he is likely to sign, represented a compromise measure between civil liberties advocates, who worry that plate readers could give police information about innocent citizens’ whereabouts, and law enforcement, who say it is a potentially a valuable tool in crime fighting.

“License plate readers are a new tool,” Shumlin said in an interview. “It’s an important tool to make law enforcement better, but the privacy concerns are real and justified, and I think the law found a good compromise.”

More than 30 law enforcement agencies across the state have deployed the readers in recent years, including police in Rutland, Hartford and Springfield, and the sheriff’s departments in Windsor and Orange counties. Readers can scan thousands of license plates an hour, allowing police to pinpoint location of drivers and check if cars are associated with arrest warrants. The information captured by plate readers is sent to the Vermont Fusion Center in Williston, which is overseen by the Vermont State Police. The federal government also has access to the data.

New Hampshire has forbidden police from using plate readers.

Police, who introduced the devices without legislative approval and little public notice in 2008, keep the data for four years, and resisted calls to significantly cut that retention period. They argue the readers can allow them to track suspect vehicles with ease.

For example, the Hartford police and other agencies deployed plate readers along the Vermont border during the manhunt for suspected Boston Marathon suspect Dzhokhar Tsarnaev, in case he evaded a police dragnet and fled to Vermont.

The Vermont chapter of the American Civil Liberties Union has asked for data to be eliminated in 30 days, saying police could easily abuse the system to gather comprehensive information about the whereabouts of citizens. But Vermont ACLU Executive Director Allen Gilbert said he was comfortable with the compromise.

“It’s pretty clear there are some people out there who are (worried) about (plate readers) and big data generally,” Gilbert said. “They don’t like the idea that government is collecting all this information about people and their movements and then storing it.”

It was only after the ACLU, along with its state chapters, filed a request for law enforcement records around the country last year that the scope of the plate readers’ data collection became apparent.

“I think 18 months is reasonable and I think it’s important that there are oversights,” Vermont Public Safety Commissioner Keith Flynn said in an interview. “At the end of the day ... it’s a good balance. Eighteen months is fair.”

Citing privacy concerns, Norwich Town Manager Neil Fulton declined a federal grant last year to purchase a plate reader for his town’s police department.